Device and method for measuring minimum integral time of avalanche photodiode

Abstract

The invention discloses a device and a method for measuring the minimum integral time of an avalanche photodiode, and relates to the technical field of measurement. The measuring device comprises a light source which is suitable for emitting an incident laser signal, and a to-be-measured avalanche photodiode detects the incident laser signal and outputs a current signal; the detection assembly is used for detecting the optical power of the incident laser signal to obtain a first detection result and detecting the current signal to obtain a second detection result; the processing assembly comprises a photon number determination module used for obtaining the average photon number of the incident laser signal in unit time according to the first detection result; the mean value and variance determination module is suitable for obtaining a mean value and a variance of the current signal according to the second detection result; and the integral time determination module is suitable for obtaining the minimum integral time of the avalanche photodiode to be measured according to the average photon number of the incident laser signal in unit time, the mean value of the current signal and the variance of the current signal.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a device for measuring the minimum integration time of a linear mode avalanche photodiode. Background Art

[0002] Avalanche photodiode is a high-performance photoelectric conversion device that uses the avalanche multiplication effect of carriers to amplify photoelectric signals to detect optical signals. Avalanche photodiodes have the advantages of small size, large current gain, high sensitivity, and fast response speed. They are suitable for detecting and receiving weak optical signals and have been widely used in optical fiber communication, laser radar, optical imaging and other fields. For avalanche photodiodes working in linear mode, the indicators for measuring their response speed mainly include response bandwidth, response time, minimum integration time, etc. These indicators jointly determine the performance of avalanche photodiodes in high-speed applications and their applicability in fast optical signal detection and communication systems. Among them, the response bandwidth refers to the frequency response of the avalanche photodetection signal, which can be directly measured by equipment such as a spectrum analyzer. The response time refers to the time required for the output current to be generated from the arrival of the optical signal at the photodiode. It is usually measured by the time from 10% to 90% of the output signal from the falling edge (or rising edge) when a pulsed optical signal is input, and can be directly measured using equipment such as an oscilloscope. The minimum integration time refers to the minimum accumulation time of the light signal that the avalanche photodiode can distinguish when measuring the light signal. It determines the optical resolution capability of the avalanche photodiode. Currently, there is no equipment or method that can directly measure it. Summary of the invention

[0003] In view of this, the present invention provides a device and a method for measuring the minimum integration time of an avalanche photodiode.

[0004] As a first aspect of the present invention, a device for measuring the minimum integration time of an avalanche photodiode is provided, the device comprising:

[0005] A light source is used to emit an incident laser signal and transmit the incident laser signal to the avalanche photodiode to be tested, so that the avalanche photodiode to be tested detects the incident laser signal and outputs a current signal; wherein the avalanche photodiode to be tested operates in a linear mode;

[0006] A detection component, adapted to detect the optical power of the incident laser signal to obtain a first detection result, and adapted to detect the current signal to obtain a second detection result;

[0007] Processing components, including:

[0008] A photon number determination module, adapted to obtain an average photon number of an incident laser signal per unit time according to the first detection result;

[0009] a mean and variance determination module, adapted to obtain a mean of the current signal and a variance of the current signal according to the second detection result;

[0010] The integration time determination module is suitable for obtaining the minimum integration time of the avalanche photodiode to be tested according to the average number of photons of the laser signal per unit time, the mean value of the current signal and the variance of the current signal.

[0011] According to an embodiment of the present invention, when the avalanche photodiode to be tested is in an AC output mode or a DC output mode, the incident laser signal is a discontinuous laser signal, and the current signal output by the avalanche photodiode to be tested includes a high-level signal and a low-level signal, wherein when the avalanche photodiode to be tested receives the incident laser signal, the avalanche photodiode to be tested outputs a high-level signal, and when the avalanche photodiode to be tested does not receive the incident laser signal, the avalanche photodiode to be tested outputs a low-level signal;

[0012] The mean and variance determination module is adapted to obtain the mean of the electric signal according to the mean of the high level signal and the mean of the low level signal, and is adapted to obtain the variance of the current signal according to the variance of the high level signal and the variance of the low level signal.

[0013] According to an embodiment of the present invention, the minimum integration time of the avalanche photodiode to be tested is expressed as follows:

[0014] ;

[0015] ;

[0016] ;

[0017] in, is the minimum integration time of the avalanche photodiode to be tested, is the mean value of the mean current signal, is the variance of the current signal, is the mean value of the high level signal, is the mean value of the low-level signal, is the variance of the high-level signal, is the variance of the low-level signal, is the average number of photons of the incident laser signal per unit time.

[0018] According to an embodiment of the present invention, the light source comprises:

[0019] The first laser is a direct current driven laser, and is suitable for emitting an initial laser signal, wherein the initial laser signal is a discontinuous laser signal;

[0020] an intensity modulator, adapted to modulate the intensity of the initial laser signal to obtain an incident laser signal; or,

[0021] Light sources include:

[0022] The second laser is a gate-driven laser adapted to emit an incident laser signal.

[0023] According to an embodiment of the present invention, the light source further comprises:

[0024] The optical attenuator is suitable for adjusting the optical power of the incident laser signal.

[0025] According to an embodiment of the present invention, when the avalanche photodiode to be tested is an avalanche photodiode in a DC output mode, the incident laser signal includes a plurality of sub-laser signals, each of which is a continuous laser signal, and the optical powers of any two sub-laser signals are different;

[0026] The current signal output by the avalanche photodiode to be tested includes a plurality of sub-current signals; each sub-current signal corresponds to each sub-laser signal one by one;

[0027] The minimum integration time of the avalanche photodiode to be tested is obtained according to the average number of photons of the laser signal per unit time, the mean value of the current signal and the variance of the current signal, including:

[0028] The minimum integration time of the avalanche photodiode to be tested is obtained according to the average number of photons of all sub-laser signals per unit time, the mean value of all sub-current signals and the variance of all sub-current signals.

[0029] According to an embodiment of the present invention, the minimum integration time of the avalanche photodiode to be tested satisfies the following relationship:

[0030] ;

[0031] ;

[0032] in, Indicates the minimum integration time of the avalanche photodiode to be tested, represents the mean value of the sub-current signal, represents the variance of the sub-current signal, represents the average number of photons per unit time of the sub-laser signal, It represents the mean value of the background noise of the avalanche photodiode to be tested. represents the variance of the background noise of the avalanche photodiode to be measured, and is the fitting coefficient.

[0033] According to an embodiment of the present invention, the light source comprises:

[0034] The first laser is a direct current driven laser, and is suitable for emitting an initial laser signal, wherein the initial laser signal is a continuous laser signal;

[0035] The optical attenuator is suitable for adjusting the optical power of the initial laser signal multiple times to obtain multiple sub-laser signals.

[0036] According to an embodiment of the present invention, the measuring device further comprises:

[0037] The amplifier is suitable for amplifying the current signal output by the avalanche photodiode to be tested, and transmitting the amplified current signal to the detection component.

[0038] The detection components include:

[0039] An optical power meter, adapted to detect the optical power of an incident laser signal to obtain a first detection result;

[0040] The oscilloscope is suitable for detecting the current signal to obtain a second detection result.

[0041] As a second aspect of the present invention, a method for measuring the minimum integration time of an avalanche photodiode is also provided, which is implemented using the above-mentioned measuring device. The measuring method includes:

[0042] The avalanche photodiode to be tested detects the incident laser signal and outputs a current signal; wherein the avalanche photodiode to be tested operates in a linear mode;

[0043] Using a detection component to detect the optical power of the incident laser signal to obtain a first detection result, and detecting the current signal to obtain a second detection result;

[0044] Obtaining the average number of photons of the incident laser signal per unit time according to the first detection result;

[0045] Obtaining a mean value of the current signal and a variance of the current signal according to the second detection result;

[0046] The minimum integration time of the avalanche photodiode to be measured is obtained according to the average number of photons of the laser signal per unit time, the mean value of the current signal and the variance of the current signal.

[0047] According to an embodiment of the present invention, the processing component obtains the minimum integration time of the avalanche photodiode to be tested by utilizing the average number of photons of the incident laser signal per unit time, the mean value of the current signal and the variance of the current signal, thereby realizing the measurement of the minimum integration time of the avalanche photodiode working in the linear mode, and further realizing accurate and comprehensive measurement of the response speed of the avalanche photodiode in the linear mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0049] Figure 1 A schematic diagram showing a device for measuring the minimum integration time of an avalanche photodiode provided in accordance with an embodiment of the present invention is shown;

[0050] Figure 2 A schematic diagram of a measuring device with a continuous light source provided according to an embodiment of the present invention is shown;

[0051] Figure 3 A schematic diagram of a measuring device with a gated light source provided according to an embodiment of the present invention is shown;

[0052] Figure 4 A schematic diagram of another measuring device with a gated light source provided according to an embodiment of the present invention is shown.

[0053] Description of Reference Numerals

[0054] 1-light source; 2-detection component; 3-processing component; 4-avalanche photodiode to be tested; 11-first laser; 12-optical attenuator; 13-intensity modulator; 14-second laser; 21-optical power meter; 22-oscilloscope; 31-photon number determination module; 32-mean and variance determination module; 33-integral time determination module. DETAILED DESCRIPTION

[0055] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0056] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0057] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0058] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0059] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present invention.

[0060] Figure 1 A device for measuring the minimum integration time of an avalanche photodiode provided according to an embodiment of the present invention is shown.

[0061] like Figure 1 As shown, the measuring device includes: a light source 1, a detection component 2 and a processing component 3.

[0062] The light source 1 is suitable for emitting an incident laser signal and transmitting the incident laser signal to the avalanche photodiode 4 to be tested, so that the avalanche photodiode 4 to be tested detects the incident laser signal and outputs a current signal; wherein the avalanche photodiode 4 to be tested operates in a linear mode. The detection component 2 is suitable for detecting the optical power of the incident laser signal to obtain a first detection result, and is suitable for detecting the current signal to obtain a second detection result. The processing component 3 includes a photon number determination module 31, a mean and variance determination module 32, and an integration time determination module 33. The photon number determination module 31 is suitable for obtaining the average number of photons of the incident laser signal per unit time according to the first detection result. The mean and variance determination module 32 is suitable for obtaining the mean of the current signal according to the second detection result, and is suitable for obtaining the variance of the current signal according to the second detection result. The integration time determination module 33 is suitable for obtaining the minimum integration time of the avalanche photodiode to be tested according to the average number of photons of the incident laser signal per unit time, the mean of the current signal, and the variance of the current signal. The mean value of the current signal is the average value of the current signal detected by the detection component 2 during the detection time of the detection component 2. The variance of the current signal is a measure of the degree of dispersion of the current signal measured by the detection component 2 from its average value during the detection time of the detection component 2.

[0063] According to an embodiment of the present invention, the processing component 3 obtains the minimum integration time of the avalanche photodiode by utilizing the average number of photons of the incident laser signal per unit time, the mean value of the current signal and the variance of the current signal, thereby realizing the measurement of the minimum integration time of the avalanche photodiode working in the linear mode, and further realizing accurate and comprehensive measurement of the response speed of the linear mode avalanche photodiode.

[0064] According to an embodiment of the present invention, the avalanche photodiode 4 to be tested may be an avalanche photodiode in an AC output mode or an avalanche photodiode in a DC output mode. For avalanche photodiodes to be tested with different output modes, the incident laser signal output by the light source 1 is also different.

[0065] According to an embodiment of the present invention, when the avalanche photodiode 4 to be tested is an avalanche photodiode in a DC output mode, the incident laser signal generated by the light source 1 includes a plurality of sub-laser signals, each of which is a continuous laser signal, and the optical powers of any two sub-laser signals are different. The current signal output by the avalanche photodiode to be tested includes a plurality of sub-current signals; each sub-current signal corresponds one-to-one to each sub-laser signal. The minimum integration time of the avalanche photodiode to be tested is obtained according to the average number of photons of the incident laser signal per unit time, the mean of the current signal, and the variance of the current signal, including: obtaining the minimum integration time of the avalanche photodiode to be tested according to the average number of photons of all sub-laser signals per unit time, the mean of all sub-current signals, and the variance of all sub-current signals.

[0066] According to an embodiment of the present invention, the light source 1 capable of generating a plurality of sub-laser signals is a continuous light source.

[0067] Figure 2 A schematic diagram of a measuring device with a continuous light source provided according to an embodiment of the present invention is shown.

[0068] like Figure 2 As shown, the light source 1 includes a first laser 11 and an optical attenuator 12. The first laser 11 is a DC-driven laser, which is suitable for emitting an initial laser signal, which is a continuous laser signal. The optical attenuator 12 is suitable for adjusting the optical power of the initial laser signal multiple times to obtain multiple sub-laser signals.

[0069] According to an embodiment of the present invention, the following describes in detail how the integration time determination module 33 obtains the minimum integration time of the avalanche photodiode to be tested by using the average number of photons of multiple sub-laser signals per unit time, the mean of all sub-current signals and the variance of all sub-current signals when the avalanche photodiode to be tested is in DC output mode.

[0070] For a sub-laser signal, its optical power is a constant, and the average number of photons per unit time is also a constant, which can be expressed as Since the avalanche photodiode under test in the DC output mode works in the linear mode, its minimum integration time is recorded as , then the minimum integration time of the sub-laser signal in the DC output mode of the avalanche photodiode to be tested is The average number of photons in It is expressed as formula (1).

[0071] (1);

[0072] when When larger ( ≥10), the sub-laser signal is within the minimum integration time number of photons in It can be approximated by a one-dimensional Gaussian distribution, expressed as formula (2).

[0073] (2);

[0074] It can be seen from equation (2) that the minimum integration time of the sub-laser signal in the avalanche photodiode to be tested in this DC output mode is number of photons in The average value (i.e. the minimum integration time of the sub-laser signal in the avalanche photodiode to be tested in this DC output mode) The average number of photons in the .

[0075] The sub-current signal output by the avalanche photodiode under test working in linear mode is used express, Satisfies formula (3).

[0076] (3);

[0077] in, is the photoelectric conversion coefficient of the avalanche photodiode to be tested, is the background noise of the avalanche photodiode to be tested, and the sub-current signal is the current value at each detection moment within the detection time period, and the detection time period refers to the time period during which the avalanche photodiode to be tested detects the sub-laser signal.

[0078] According to formula (3), within the detection period, the mean value of the sub-current signal is expressed as formula (4), and the variance of the sub-current signal is expressed as formula (5)

[0079] (4);

[0080] in, represents the mean value of the sub-current signal, Indicates the minimum integration time of the sub-current signal in the avalanche photodiode to be tested number of photons in The mean value of the sub-current signal during the minimum integration time of the avalanche photodiode to be tested The average number of photons in Represents the mean value of the noise floor.

[0081] (5);

[0082] in, represents the variance of the sub-current signal, Indicates the minimum integration time of the avalanche photodiode under test in the DC output mode number of photons in The variance of Represents the variance of the noise floor.

[0083] make , then:

[0084] (6).

[0085] According to the embodiment of the present invention, the optical attenuator 12 can be used to adjust the first laser 11 to obtain multiple sub-laser signals. Since the optical powers of the obtained multiple sub-laser signals are different, the average number of photons per unit time of the sub-laser signals can be adjusted by adjusting the optical attenuator 12. Adjustment ( The adjustment range is 100~10000 / 100ps).

[0086] According to formula (6), the fitting coefficient can be obtained by fitting the average number of photons per unit time of all sub-laser signals, the mean of all sub-current signals and the variance of all sub-current signals (for example, MATLAB can be used for data fitting). and , and then get the minimum integration time of the avalanche photodiode to be tested .

[0087] According to the embodiment of the present invention, based on the above content, it can be seen that for the avalanche photodiode to be tested in the DC output mode, multiple continuous sub-laser signals can be used to achieve the measurement of the minimum integration time of the avalanche photodiode. However, for the avalanche photodiode in the AC output mode, when a continuous laser signal is used, the mean value of the current signal outputted by the avalanche photodiode is always maintained near 0, so the above method is not applicable to the avalanche photodiode working in the AC output mode.

[0088] According to an embodiment of the present invention, a discontinuous laser signal can be generated by using a light source 1 to measure an avalanche photodiode operating in an AC output mode or an avalanche photodiode operating in a DC output mode. The light source 1 capable of generating a discontinuous laser signal can be a gated light source, which can be in two forms, which are described below.

[0089] Figure 3 A schematic diagram of a measuring device with a gated light source provided according to an embodiment of the present invention is shown.

[0090] like Figure 3As shown, it is a gated light source in the first form, and the gated light source may include, for example, a first laser 11 and an intensity modulator 13. The first laser 11 is a DC-driven laser, and is suitable for emitting an initial laser signal, and the initial laser signal is a continuous laser signal. The intensity modulator 13 is suitable for modulating the intensity of the initial laser signal to obtain an incident laser signal. The intensity modulator 13 can realize that the light source outputs a discontinuous incident laser signal (gated light signal) by changing the amplitude or intensity of the incident laser signal. When the intensity modulator 13 is in the "on" state (i.e., when the gate is open), it allows the incident laser signal to pass through and maintain a certain intensity; when the intensity modulator 13 is in the "off" state (i.e., when the gate is closed), it blocks the passage of the incident laser signal.

[0091] Figure 4 A schematic diagram of another measuring device with a gated light source provided according to an embodiment of the present invention is shown.

[0092] like Figure 4 As shown, a gated light source in a second form includes a second laser 14, which is a gate-driven laser and is suitable for emitting an incident laser signal. When the second laser 14 is a gate-driven laser, the incident laser signal generated by it is a discontinuous laser signal, so when the second laser 14 is a gate-driven laser, the intensity modulator 13 is not required.

[0093] According to an embodiment of the present invention, when the door is open, the light source 1 emits an incident laser signal, and when the door is closed, the light source 1 does not output an incident laser signal. When the light source 1 outputs an incident current signal, the avalanche photodiode to be tested operating in the AC output mode or the DC output mode outputs a high level signal. When light source 1 does not output a signal, the avalanche photodiode under test working in the AC output mode or the DC output mode outputs a low-level signal. The mean and variance determination module 32 is adapted to obtain the mean of the current signal according to the mean of the high level signal and the mean of the low level signal, and to obtain the variance of the current signal according to the variance of the high level signal and the variance of the low level signal.

[0094] The mean value of the current signal is expressed as formula (7), and the variance of the current signal is expressed as formula (8).

[0095] (7);

[0096] (8);

[0097] in, is the mean value of the high level signal, is the variance of the high-level signal, is the mean value of the low-level signal, is the variance of the low-level signal, is the average number of photons of the incident laser signal per unit time, is the mean value of the current signal (mean value of the peak-to-peak value), is the variance of the current signal (the variance of the peak-to-peak value). is the minimum integration time of the incident laser signal The average number of photons in the

[0098] Using equations (7) to (8), we can obtain equation (9).

[0099] (9).

[0100] According to formula (9), the minimum integration time of the avalanche photodiode to be tested working in AC output mode or DC output mode can be obtained: .

[0101] According to an embodiment of the present invention, when the light source 1 generates a discontinuous laser signal, the light source 1 further includes: an optical attenuator 12, which is suitable for adjusting the optical power of the incident laser signal. By adjusting the optical power of the incident laser signal by the optical attenuator 12, the minimum integration time of the avalanche photodiode to be tested in the AC output mode or the DC output mode can be measured. The optical attenuator 12 is also used to ensure that the incident laser signal has a suitable optical power, so as not to cause damage to the detection component 2.

[0102] According to an embodiment of the present invention, the above-mentioned measuring device further comprises: an amplifier (not shown in the figure) adapted to amplify the current signal output by the avalanche photodiode to be measured, and transmit the amplified current signal to the detection component 2 .

[0103] According to an embodiment of the present invention, the detection component 2 includes: an optical power meter 21 and an oscilloscope 22 .

[0104] The optical power meter 21 is suitable for detecting the optical power of the incident laser signal to obtain a first detection result, and the oscilloscope 22 is suitable for detecting the current signal to obtain a second detection result.

[0105] According to an embodiment of the present invention, the photon number determination module 31, the mean and variance determination module 32, and the integration time determination module 33 can be combined in one module, or any one of the modules can be split into multiple modules. Alternatively, at least part of the functions of one or more of these modules can be combined with at least part of the functions of other modules and implemented in one module. According to an embodiment of the present invention, at least one of the photon number determination module 31, the mean and variance determination module 32, and the integration time determination module 33 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware, and firmware, or in any appropriate combination of any of them. Alternatively, at least one of the photon number determination module 31, the mean and variance determination module 32, and the integration time determination module 33 can be at least partially implemented as a computer program module, and when the computer program module is run, the corresponding function can be executed.

[0106] As a second aspect of the present invention, a method for measuring the minimum integration time of an avalanche photodiode is provided, which is implemented using the above-mentioned measuring device. The method includes operations S1 to S5.

[0107] In operation S1, the avalanche photodiode to be tested detects the incident laser signal and outputs a current signal; wherein the avalanche photodiode to be tested operates in a linear mode.

[0108] In operation S2, the optical power of the incident laser signal is detected by the detection component to obtain a first detection result, and the current signal is detected to obtain a second detection result.

[0109] In operation S3, the average number of photons of the incident laser signal per unit time is obtained according to the first detection result.

[0110] In operation S4 , a mean value of the current signal and a variance of the current signal are obtained according to the second detection result.

[0111] In operation S5, the minimum integration time of the avalanche photodiode to be tested is obtained according to the average number of photons of the laser signal per unit time, the mean value of the current signal, and the variance of the current signal.

[0112] The measuring device provided according to the embodiment of the present invention can effectively measure the performance indicator of the minimum integration time of the avalanche photodiode working in the linear mode, thereby promoting the application of the avalanche photodiode working in the linear mode in the fields of fast optical signal detection and communication systems.

[0113] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A device for measuring the minimum integration time of an avalanche photodiode, characterized in that: include: A light source, adapted to emit an incident laser signal and transmit the incident laser signal to an avalanche photodiode to be tested, so that the avalanche photodiode to be tested detects the incident laser signal and outputs a current signal; wherein the avalanche photodiode to be tested operates in a linear mode; A detection component, adapted to detect the optical power of the incident laser signal to obtain a first detection result, and adapted to detect the current signal to obtain a second detection result; Processing components, including: A photon number determination module, adapted to obtain an average photon number of the incident laser signal per unit time according to the first detection result; a mean and variance determination module, adapted to obtain a mean of the current signal and a variance of the current signal according to the second detection result; The integration time determination module is adapted to obtain the minimum integration time of the avalanche photodiode to be tested according to the average number of photons of the incident laser signal per unit time, the mean value of the current signal and the variance of the current signal.

2. The measuring device according to claim 1, characterized in that When the avalanche photodiode to be tested is in an AC output mode or a DC output mode, the incident laser signal is a discontinuous laser signal, and the second detection result includes a high-level signal and a low-level signal, wherein when the avalanche photodiode to be tested receives the incident laser signal, the avalanche photodiode to be tested outputs a high-level signal, and when the avalanche photodiode to be tested does not receive the incident laser signal, the avalanche photodiode to be tested outputs a low-level signal; The mean and variance determination module is adapted to obtain the mean of the current signal according to the mean of the high level signal and the mean of the low level signal, and is adapted to obtain the variance of the current signal according to the variance of the high level signal and the variance of the low level signal.

3. The measuring device according to claim 2, characterized in that The minimum integration time of the avalanche photodiode to be tested is expressed as follows: ； ； ； in, is the minimum integration time of the avalanche photodiode to be tested, is the mean value of the current signal, is the variance of the current signal, is the mean value of the high level signal, is the mean value of the low level signal, is the variance of the high level signal, is the variance of the low-level signal, is the average number of photons of the incident laser signal per unit time.

4. The measuring device according to claim 2, characterized in that The light source comprises: The first laser is a direct current driven laser, and is suitable for emitting an initial laser signal, wherein the initial laser signal is a discontinuous laser signal; an intensity modulator, adapted to modulate the intensity of the initial laser signal to obtain the incident laser signal; or The light source comprises: The second laser is a gate-driven laser, adapted to emit the incident laser signal.

5. The measuring device according to claim 4, characterized in that The light source also includes: The optical attenuator is suitable for adjusting the optical power of the incident laser signal.

6. The measuring device according to claim 1, characterized in that When the avalanche photodiode to be tested is an avalanche photodiode in a DC output mode, the incident laser signal includes a plurality of sub-laser signals, each of which is a continuous laser signal, and the optical powers of any two sub-laser signals are different; The current signal output by the avalanche photodiode to be tested includes a plurality of sub-current signals; each sub-current signal corresponds to each sub-laser signal one by one; The minimum integration time of the avalanche photodiode to be measured is obtained according to the average number of photons of the laser signal per unit time, the mean value of the current signal and the variance of the current signal, including: The minimum integration time of the avalanche photodiode to be measured is obtained according to the average number of photons of all sub-laser signals per unit time, the mean value of all sub-current signals and the variance of all sub-current signals.

7. The measuring device according to claim 6, characterized in that The minimum integration time of the avalanche photodiode to be tested satisfies the following relationship: ； ； in, represents the minimum integration time of the avalanche photodiode to be tested, represents the mean value of the sub-current signal, represents the variance of the sub-current signal, represents the average number of photons per unit time of the sub-laser signal, represents the mean value of the background noise of the avalanche photodiode to be tested, represents the variance of the background noise of the avalanche photodiode to be measured, and is the fitting coefficient.

8. The measuring device according to claim 6, characterized in that The light source comprises: The first laser is a direct-current driven laser, and is adapted to emit an initial laser signal, wherein the initial laser signal is a continuous laser signal; The optical attenuator is adapted to adjust the optical power of the initial laser signal multiple times to obtain the multiple sub-laser signals.

9. The measuring device according to claim 1, characterized in that The measuring device further comprises: an amplifier adapted to amplify the current signal output by the avalanche photodiode to be measured and transmit the amplified current signal to the detection component; The detection component comprises: An optical power meter, adapted to detect the optical power of the incident laser signal to obtain a first detection result; The oscilloscope is suitable for detecting the current signal to obtain a second detection result.

10. A method for measuring the minimum integration time of an avalanche photodiode, implemented by using the measuring device according to any one of claims 1 to 9, characterized in that: The measuring method comprises: The avalanche photodiode to be tested detects the incident laser signal and outputs a current signal; wherein the avalanche photodiode to be tested operates in a linear mode; Using a detection component to detect the optical power of the incident laser signal to obtain a first detection result, and detecting the current signal to obtain a second detection result; Obtaining the average number of photons of the incident laser signal per unit time according to the first detection result; Obtaining a mean value of the current signal and a variance of the current signal according to the second detection result; The minimum integration time of the avalanche photodiode to be measured is obtained according to the average number of photons of the laser signal per unit time, the mean value of the current signal and the variance of the current signal.

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